allow configuring the escape delay timeout

Introduce a "fish_escape_delay_ms" variable to allow the user to configure the
delay used when seeing a bare escape before assuming no other characters will
be received that might match a bound character sequence. This is primarily
useful for vi mode so that a bare escape character (i.e., keystroke) can
switch to vi "insert" to "normal" mode in a timely fashion.

5 files changed, 146 insertions, 55 deletions

diff --git a/src/env.cpp b/src/env.cpp
index 3d7023db..527ed253 100644
--- a/src/env.cpp
+++ b/src/env.cpp
@@ -303,7 +303,7 @@ static void handle_locale()
 }
 
 
-/** React to modifying hte given variable */
+/** React to modifying the given variable */
 static void react_to_variable_change(const wcstring &key)
 {
     if (var_is_locale(key))
@@ -319,6 +319,10 @@ static void react_to_variable_change(const wcstring &key)
     {
         reader_react_to_color_change();
     }
+    else if (key == L"fish_escape_delay_ms")
+    {
+        update_wait_on_escape_ms();
+    }
 }
 
 /**
diff --git a/src/input_common.cpp b/src/input_common.cpp
index cda4ca11..291a37a7 100644
--- a/src/input_common.cpp
+++ b/src/input_common.cpp
@@ -33,9 +33,11 @@ Implementation file for the low level input library
    reading after \\x1b is read before assuming that escape key was
    pressed, and not an escape sequence.
 
-   This is the value used by the readline library.
+   This is the value used by the readline library. It can be overridden by
+   setting the fish_escape_delay_ms variable.
 */
-#define WAIT_ON_ESCAPE 500
+#define WAIT_ON_ESCAPE_DEFAULT 500
+static int wait_on_escape_ms = WAIT_ON_ESCAPE_DEFAULT;
 
 /** Characters that have been read and returned by the sequence matching code */
 static std::deque<wint_t> lookahead_list;
@@ -79,6 +81,7 @@ static int (*interrupt_handler)();
 void input_common_init(int (*ih)())
 {
     interrupt_handler = ih;
+    update_wait_on_escape_ms();
 }
 
 void input_common_destroy()
@@ -214,36 +217,48 @@ static wint_t readb()
     return arr[0];
 }
 
+// Update the wait_on_escape_ms value in response to the fish_escape_delay_ms
+// user variable being set.
+void update_wait_on_escape_ms()
+{
+    env_var_t escape_time_ms = env_get_string(L"fish_escape_delay_ms");
+    if (escape_time_ms.missing_or_empty())
+    {
+        wait_on_escape_ms = WAIT_ON_ESCAPE_DEFAULT;
+        return;
+    }
+
+    wchar_t *endptr;
+    long tmp = wcstol(escape_time_ms.c_str(), &endptr, 10);
+
+    if (*endptr != '\0' || tmp < 10 || tmp >= 5000)
+    {
+        fwprintf(stderr, L"ignoring fish_escape_delay_ms: value '%ls' "
+                "is not an integer or is < 10 or >= 5000 ms\n",
+                escape_time_ms.c_str());
+    }
+    else
+    {
+        wait_on_escape_ms = (int)tmp;
+    }
+}
+
+
 wchar_t input_common_readch(int timed)
 {
     if (! has_lookahead())
     {
         if (timed)
         {
-            int count;
             fd_set fds;
-            struct timeval tm=
-            {
-                0,
-                1000 * WAIT_ON_ESCAPE
-            }
-            ;
-
             FD_ZERO(&fds);
             FD_SET(0, &fds);
-            count = select(1, &fds, 0, 0, &tm);
-
-            switch (count)
+            struct timeval tm = {wait_on_escape_ms / 1000,
+                                 1000 * (wait_on_escape_ms % 1000)};
+            int count = select(1, &fds, 0, 0, &tm);
+            if (count <= 0)
             {
-                case 0:
-                    return WEOF;
-
-                case -1:
-                    return WEOF;
-                    break;
-                default:
-                    break;
-
+                return WEOF;
             }
         }
 
diff --git a/src/input_common.h b/src/input_common.h
index 5ec34b39..72ccc073 100644
--- a/src/input_common.h
+++ b/src/input_common.h
@@ -35,6 +35,9 @@ void input_common_init(int (*ih)());
 */
 void input_common_destroy();
 
+// Adjust the escape timeout.
+void update_wait_on_escape_ms();
+
 /**
    Function used by input_readch to read bytes from stdin until enough
    bytes have been read to convert them to a wchar_t. Conversion is
diff --git a/tests/bind.expect b/tests/bind.expect
index 6c80b8f1..9bde0689 100644
--- a/tests/bind.expect
+++ b/tests/bind.expect
@@ -2,59 +2,124 @@
 spawn $fish
 expect_prompt
 
-# Test switching key bindings to vi mode.
-# This should leave the mode in the appropriate state (i.e., insert mode).
+# Test switching key bindings to vi mode. This should leave the mode in the
+# appropriate state (i.e., insert mode). These initial tests assume the
+# default escape timeout of 500ms is in effect.
 
 send "set -g fish_key_bindings fish_vi_key_bindings\r"
 expect_prompt
-send -h "echo fail\033"
+send "echo fail: default escape timeout"
+send "\033"
 # Delay needed to allow fish to transition to vi "normal" mode.
 sleep 0.510
-send -h "ddiecho success\r"
-expect_prompt -re {\r\nsuccess\r\n} {
-    puts "vi replace line success"
+send "ddi"
+send "echo success: default escape timeout\r"
+expect_prompt -re {\r\nsuccess: default escape timeout\r\n} {
+    puts "vi replace line: default escape timeout"
 } -nounmatched -re {\r\nfail} {
-    puts stderr "vi replace line fail"
+    puts stderr "vi replace line fail: default escape timeout"
 } unmatched {
-    puts stderr "Couldn't find expected output 'success'"
+    puts stderr "couldn't find expected output: replace line, default escape timeout"
 }
 
 # Verify that a human can transpose words using \et (which is an emacs default
 # binding but should be valid while in vi insert mode).
-send "echo abc def\033"
-# Fish should still be in vi "insert" mode after this delay.
+send "echo abc def"
+send "\033"
+# Fish should still be in vi insert mode after this delay to simulate a slow
+# typist.
 sleep 0.400
 send "t\r"
 expect_prompt -re {\r\ndef abc\r\n} {
-    puts "vi transpose words success"
+    puts "vi transpose words: default escape timeout"
 } unmatched {
-    puts stderr "vi transpose words fail"
+    puts stderr "vi transpose words fail: default escape timeout"
 }
 
 # Test replacing a single character.
-send -h "echo TEXT\033"
+send "echo TEXT"
+send "\033"
 # Delay needed to allow fish to transition to vi "normal" mode.
 sleep 0.510
-send -h "hhrAi\r"
+send "hhrAi\r"
 expect_prompt -re {\r\nTAXT\r\n} {
-    puts "vi mode replace success"
+    puts "vi mode replace: default escape timeout"
 } -nounmatched -re {\r\nfail} {
-    puts stderr "vi mode replace fail"
+    puts stderr "vi mode replace fail: default escape timeout"
 } unmatched {
-    puts stderr "Couldn't find expected output 'TAXT'"
+    puts stderr "couldn't find expected output 'TAXT': default escape timeout"
+}
+
+# Verify that changing the escape timeout has an effect. The vi key bindings
+# should still be in effect.
+send "set -g fish_escape_delay_ms 100\r"
+expect_prompt
+send "echo fail: shortened escape timeout"
+send "\033"
+sleep 0.110
+send "ddi"
+send "echo success: shortened escape timeout\r"
+expect_prompt -re {\r\nsuccess: shortened escape timeout\r\n} {
+    puts "vi replace line: shortened escape timeout"
+} -nounmatched -re {\r\nfail} {
+    puts stderr "vi replace line fail: shortened escape timeout"
+} unmatched {
+    puts stderr "couldn't find expected output: replace_line, shortened escape timeout"
+}
+
+# Verify that we don't switch to vi normal mode if we don't wait long enough
+# after sending escape. The vi key bindings should still be in effect.
+send "echo fail: no normal mode"
+send "\033"
+sleep 0.050
+send "ddi"
+send "inserted\r"
+expect_prompt -re {\r\nfail: no normal modediinserted\r\n} {
+    puts "vi normal mode: shortened escape timeout"
+} -nounmatched -re {\r\nfail} {
+    puts stderr "vi normal mode fail: shortened escape timeout"
+} unmatched {
+    puts stderr "couldn't find expected output: no normal mode"
 }
 
 # Switch back to regular (emacs mode) key bindings.
-send -h "set -g fish_key_bindings fish_default_key_bindings\r"
+send "set -g fish_key_bindings fish_default_key_bindings\r"
+expect_prompt
+
+# Verify the emacs transpose word (\et) behavior using various delays,
+# including none, after the escape character.
+
+# Start by testing with no delay. This should transpose the words.
+send "echo abc def"
+send "\033t\r"
+expect_prompt -re {\r\ndef abc\r\n} {
+    puts "emacs transpose words: no escape delay"
+} unmatched {
+    puts stderr "emacs transpose words fail: no escape delay"
+}
+
+# Now test with a delay > 0 and < the escape timeout. This should transpose
+# the words.
+send "set -g fish_escape_delay_ms 100\r"
 expect_prompt
-send "echo success\r"
-expect_prompt -re {\r\nsuccess\r\n} {
-    puts "emacs success"
-} unmatched {
-    puts stderr "Couldn't find expected output 'success'"
-} timeout {
-    set msg ""
-    append msg "Timeout after setting fish_key_bindings to fish_default_key_bindings\n" \
-               "\$fish_bind_mode is most likely still set to 'insert'"
-    abort $msg
+send "echo ghi jkl"
+send "\033"
+sleep 0.050
+send "t\r"
+expect_prompt -re {\r\njkl ghi\r\n} {
+    puts "emacs transpose words: short escape delay"
+} unmatched {
+    puts stderr "emacs transpose words fail: short escape delay"
+}
+
+# Now test with a delay > the escape timeout. The transposition should not
+# occur and the "t" should become part of the text that is echoed.
+send "echo mno pqr"
+send "\033"
+sleep 0.110
+send "t\r"
+expect_prompt -re {\r\nmno pqrt\r\n} {
+    puts "emacs transpose words: long escape delay"
+} unmatched {
+    puts stderr "emacs transpose words fail: long escape delay"
 }
diff --git a/tests/bind.expect.out b/tests/bind.expect.out
index f82eec23..f4682d2c 100644
--- a/tests/bind.expect.out
+++ b/tests/bind.expect.out
@@ -1,4 +1,8 @@
-vi replace line success
-vi transpose words success
-vi mode replace success
-emacs success
+vi replace line: default escape timeout
+vi transpose words: default escape timeout
+vi mode replace: default escape timeout
+vi replace line: shortened escape timeout
+vi normal mode: shortened escape timeout
+emacs transpose words: no escape delay
+emacs transpose words: short escape delay
+emacs transpose words: long escape delay